Electronic bore gauge



Jan. 8, 1952 J. J. NEFF 2,581,495

ELECTRONIC some GAUGE Filed Aug. 18, 1945 2 SHEETS-SHEET l cflmflenwr JOSEPH J NEFF AT TORNE Y Jan. 8, 1952 J. .1. NEFF 2,581,495

ELECTRONIC BORE GAUGE 2 SHEETS-SHEET 2 Filed Aug. 18, 1945 ELECTRONIC as VOLTMETER VACUUM TUBE Jmwzztm JOSEPH NFF OSCILLATOR I ATTORNEY Patented Jan. 8, 1952 ELECTRONIC BORE GAUGE Joseph J. Neff, South Euclid, Ohio, assignor, by mesne assignments, to Jack & Heintz Precision Industries,Inc., Cleveland, Ohio, a corporation I of Delaware Application August 18, 1945, Serial No. 611,314 2 Claims. (01. 33-478) .ThiS. invention relates to measuringinstruments and hasfor one of its primary objects to provide an electronic gauge that will be capable of precision measurement of the diameter and concentricity, throughout a given longitudinal distance, of the bore of a piece of work.

Another object is to provide an improved work support containing an electrical displacement pickup unit and a positioning element andstylus with resilient means permitting longitudinal movement of the work over the positioning element and stylusand other resilient means that will'permit radial floating to. compensate for inadvertent radial thrusts. imposed by manual handling of the work on the gauge to eliminate error that would be otherwise introduced.

With the foregoing and other objects in view the invention resides in the combination of parts and in the details of construction set forth in the following description and appended claims, certain embodiments thereof being illustrated in the accompanying drawings in which:

Figure 1 is a view in elevation of the measuring device without the work, showing the work sup port in vertical section;

Figure 2 is a view showing the work and support in vertical section and the remainder of the instrument in elevation with the displacement pickup unit tilted slightly on itsfloating resilient uppor and Figure 3 is a view in vertical section taken at right angles to Figure 1 showing the measuring device, without the work showing the displacement pickup mechanism and diagrammatically the oscillator and electronic voltmeter circuits.

Referring more particularly to the drawings, the displacement pickup unit and the oscillator and voltmeter circuits maybe of the same type as shown in the United States patent to Joseph J. Neil, No. 2,361,788, dated October 31, 1944, for Displacement Pickup and the United States patent to Joseph J. Nefi, No. 2,397,196, dated March 26, 1946, for Measuring Instrument. As shown in Figure 3, it may include a coil form I for supporting a driving coil 2 and a pickup coil 3 on one side and a pickup coil 4 on the other side of the driving coil. An armature 5 is carried by a stylus arm 5 pivoted at I to move the armature longitudinally in either direction.

The instrument comprises a base t and hollow cylinder 9 to which latter a pair of opposed vertical leaf springs Ill and II are secured at I2 and I3. The top end of leaf spring H3 is connected by bolts I 4 to a gauge head housing I5 and the top end of leaf spring I I is connected by bolts I6 to a vertical member I! which is secured near 2 its bottom by apair of bolts I8 to the gauge head housing I5 to support the latter in such a manner as to permit the gauge head housing IE to bedis placed about bolts l2 and I3 in either lateral direction through the vertical slot I9 extending through the cylinder 9;

The coil form I for the driving and pickup coils 2, 3 and 4 is suitably mounted to be housed in gauge head housing I5. As viewed in Figure the stylus arm 6 is spring urged counterclockwise about its pivot I in the gauge head housing I5 by a tension spring 20 connected to the stylus arm below its pivot and extending through a transverse hole 2i tobe anchored at its other end at 22. An adjustable abutment screw bolt 23 may also be provided to abut and limit the extent of counterclockwise movement of the stylus arm Ii.

Loosely arranged about cylinder 9 is a sleeve'M with a circular flange 25. This sleeve 24 rests on a compression coil spring 25 whose other end rests on base 8. Member I! has an enlarged portion 27 that has a rigid stylus member 28 that is disposed from the ball 2% of the pivoted stylust. Suitably secured tocylinder 9 is a top circular cover plate 39 of greater outside diameter than the inside diameter of sleeve 24. Extending through the cover plate and into member?! is a set screwil having a conical tip 32 to engage a bevel edge 33 of cylinder I5 to pry the cylinder l5 and member I! apart for transverse adjustment between the normal parallel relationship between members I5 and I! about bolts I8 as a pivot for consequent radial adjustment of the rigid stylus member 28.

The work to bemeasured is shown at 1 4 having a small bore 35 and a larger lower boreLlB and having a flange 3'! resting on the work supporting A flange 25. Theoutside diameter of the top cover plate 38 is onlylslightly less than the inner diameter of bore 3% but considerably greater than the inner diameter of bore 35. The desired measurement is that of bore 36 throughout its length to determine its inner diameter and concentricity. Pressure is exerted downwardly on the work 34 which forces sleeve 24 downwardly against the action of spring 26. This brings the rigid stylus member 28 and the diametrically opposed movable stylus ball 29 into engagement with the inner surface of bore 35, as shown in Figure 2. Vertical movement of the work will, through the displacement pickup unit, oscillator and electronic volt- 7 meter, indicate the diameter of the bore throughout its length and the existence of any longitudinal taper in the bore by means of the movement of the stylus arm moving the armature inside of the driving and pickup coils. Movement of the work circularly 180 not only measures the diameter of the bore but also is concentricity.

If it were not for the provision of the leaf springs l and H, and the floating mount that they provide for members l5 and IT through slot l9 about; bolts 18 as a pivot in either direction, a lateral shift of the work 34 to the right on flange 25, as is shown in Figure 2, would cause a certain pressure on the movable stylus ball 29 in that direction and render the bore measurement indication erroneous. This, however, is compensated for by the two leaf springs which are disposed in the vertical planes of the movable stylus bal1 29 and the rigid stylus member 28. The leaf springs resiliently oppose this transverse movement of the work but permit a floating of the members l5 and 11 about bolts I8 as apivot. This causes the rigid stylus member 28 to be hard against the inner surface of the bore 36 at all times and hence the movable stylus ball 29 is at all times properly engaging the bore regardless of small misalignments of the axis of the bore with that of sleeve 24.

As is the case in the previously mentioned patent and application, measurement by the instrument is dependent upon the position of armature 5 Within coils 2, 3 and 4. When the driving coil 2 receives a signal from the oscillator 38, opposing induced voltages are set up in pickup coils 3 and 4. When armature 5 is in the electrical center of the three coils the opposing induced voltages in pickup coils 3 and 4 exactly counter balance each other and no indication will be given by the voltmeter 39. However, if by the engagement of the movable stylus ball 29 with the bore 36 the stylus arm 6 is caused to pivot in a clockwise direction the armature 5 is accordingly displaced from its electrical center. More voltage will be induced in one pickup coil than in the other resulting in a corresponding reading on the dial of the electronic voltmeter.

The adjustment set screw 3| is accessible either with or without the work in place and is for relatively minute adjustment of the bore engaging rigid stylus member 28.

I claim: 1. In an electrical measuring instrument for measuring the inside diameter of the bore of a piece of work as to its concentricity and longitudinal taper, a housing, a base and a pair of longitudinally extending parallel leaf springs each having one end connected to said base, a displacement pickup unit supported by said housing and including a pair of pickup coils and an armature, a stylus for carrying said armature for linear movement within said coils, said housing for said pickup unit being connected to the other ends of said leaf springs tobe supported thereby in spaced relationship with said base,

said leaf springs being adapted to oppose movements of said housing, work supporting means, means for resiliently supporting said work supporting means slidably about said housing for longitudinal movement relative thereto, a work engaging member on said stylus adjacent one of said leaf springs, a rigid Work engaging member on said housing diametrically opposite the work engaging member on said stylus and adjacent the other leaf spring.

displacement pickup unit supported by said housing and including a pair of pickup coils and an armature, a stylus for carrying said armature for linear movement within said coils, said housing for said pickup unit being connected to the other ends of said leaf springs to be supported thereby in spaced relation with said base, said leaf springs being adapted to resiliently oppose movements of said housing, work supporting means, means for resiliently supporting said work supporting means slidably about said housing for movement relative thereto, work engaging member on said stylus adjacent one of said leaf springs, a rigid work engaging member on said housingdiametrically opposite the work engaging member on said stylus and adjacent the other leaf spring and adjustment means on said housing forselectively adjusting said rigid Work engaging member radially with respect to the bore of the work.

JOSEPH J. NEFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,206,202 Bright Nov. 28, 1916 1,472,195 Schlakpitz Oct. 30,1923 2,065,951 Terry Dec. 29, 1936 2,200,885 Johnson May 14, 1940 2,361,788 Neff Oct. 31, 1944 2,378,334 Sirvent June 12,1945 2,397,196 Neff Mar. 26, 1946 2,411,292 Rappl Nov. 19, 1946 2,427,152 Moore Sept. 9, 1947 2,432,384 Cornell -1--- Dec. 9, 1947 2,439,595 Cooke Apr. 13, 1948 2,454,159 Graves Nov. 16, 1948 FOREIGN PATENTS Number Country Date 519,551 Great Britain Mar. 29, 1940 

